Steam iron metallic sealing structure

ABSTRACT

The invention discloses a metallic sealing structure for steam and steam-powered spray irons which use a thin ridged aluminum gasket disposed between a coverplate and the soleplate for sealing a steam generating and steam distributing cavity to confine steam flow in desired channels.

D United States Patent 1 1 3,593,441

[72] inventor Bryce A. Danton [56] References Cited [2U App No ggg'gg UNITEDSTATES PATENTS {22] Filed" mflsmg 2,127,372 8/1938 Victoretal 38/77.83x [45] Patemed Mymml 2,871,587 2/1959 Jepson 38/77.83X 3,151,869 10/1964 Butcher 277/209 [73] Assignee GeneralElectricCompany [54] STEAM IRON METALLIC SEALING STRUCTURE 8 Claims, 4 Drawing Figs.

[52] U.S.Cl 38/7733 D06! 75/06 [50] Field of Search 38/775,

Primary ExaminerPatrick D. Lawson Attorneys-Lawrence R. Kempton, Leonard J. Platt, John F. Cullen, Frank L. Neuhauser, Oscar B, Waddell and Joseph B. Forman ABSTRACT: The invention discloses a metallic sealing structure for steam and steam-powered spray irons which use a thin ridged aluminum gasket disposed between a coverplate and the soleplate for sealing a steam generating and steam distributing cavity to confine steam flow in desired channels.

PATENTE'I] mo m1 3 593441 I nventor Brg ce A. Danton M? QMMIW Attorneu STEAM IRON METALLIC SEALING STRUCTURE BACKGROUND OF THE INVENTION 1. Field ofthe Invention This invention is directed to a steam iron and, more particularly, to a steam-powered spray iron that uses a novel and thin metallic aluminum-ridged sealing member that is disposed between a coverplate and the soleplate to separate the steam generating cavity from a steam-distributing cavity and maintain a pressure tight seal between the two different pressure cavities over a long period of time with substantially no deterioration and consequent leakage.

2. Description of the Prior Art In most steam irons, steam is generated in a small cavity in the soleplate and subsequently distributed under pressure to apertures in the soleplate and to the fabric being ironed. Such irons are generally built up in a sandwichlike fashion with a cover placed over the steam-generating cavity to form a chamber and the cover and soleplate are clamped together with a seal or gasket between. Some irons, as shown in US. Pat. No. 3,041,257 of common assignment, use steam pressure to operate a sprayer and are known as powered spray irons. In such irons, suitable valving permits the steam pressure to be raised and directed to the spray nozzle where, by aspiration and pressurization of the water, depression of a control button provides a continuous powered spray until the button is released. Such an iron may use a higher steam pressure than one without the power spray. Consequently, there is more of a tendency for the higher pressure steam in the generating cavity to leak into other parts of the iron with reduction in efficiency. It is also customary to provide a pressure regulator to determine steam flow to the soleplate apertures and permit the proper steam pressure buildup in the iron before distributing it to the soleplate. In such steam irons and particularly in the steam-powered spray iron, where the pressure required to operate the spray is a factor, the problem of obtaining a permanent seal between the soleplate and the steam generating cavity coverplate has resisted solution. Many materials have been tried, including asbestos, rubbers, epoxies, fluorocarbon and chlorofluorocarbon rubbers and resins, and many silicone compounds as well as numerous sealants and adhesives. Generally, the silicones have been the most successful but they eventually deteriorate and cause leaks. Additionally, the silicones, while deteriorating with age, give off a substance which deposits on the internal parts of the iron causing those parts to become nonwettable, a phenomenon that is known as drifilm which prevents smooth water flow and is an anathema to the proper operation of a steam iron that, relatively speaking, operates under low pressures and through very small passageways. When the valve controlling water flow to the steam generator becomes drifilmed, the steam rate is reduced. A lower steam rate is combination with leaks causes a low spray rate or a poor sprayer. Similarly, whether drifilmed or not, seal leaks create the same poor operating result so that with drifilming the adverse effects are cumulative. The silicone seal alone usually fails in the high pressure area, i.e., the area between the steam cavity and distribution cavity, after two to four years operation. The other materials, as noted above, have all failed in a shorter time than silicone. Other seals made up of multiple layers have been used but have their drawbacks in the same premature failure as well as being higher cost as their complexity increases. One of the difficulties has been that aluminum parts are generally used in an iron for good heat distribution and the coverplate over the steam-generating cavity must be sealed to the generating cavity with relatively light pressure, eg 27 inch pounds of torque on each of about I2 screws. The aluminum alloy is relatively soft and hence the screws cannot be tightened down as in the head gasket of an internal combustion-engine, without distortion which causes leaks.

Prior art construction'has not provided a simple and inexpensive metallic aluminum seal of satisfactory design that may be used in a steam iron and particularly in a steam-powered spray iron that does not develop leaks in an unacceptably short period of time with consequent unsatisfactory iron performance.

SUMMARY OF THE INVENTION Briefly described, the present invention is directed to a steam iron and particularly to a steam-powered spray iron that has a soleplate with a steam-generating cavity and a steam distributing cavity that is connected to a series of steam discharge apertures in the soleplate. The iron is provided with a pressure-regulating means between the cavities to control steam flow between the cavities and to the apertures. A button is provided to actuate the sprayer under steam pressure from the generating cavity all in a known manner. To this general combination an improved sealing structure is provided between the generating and distributing cavities which comprises a coverplate over the cavities so that chambers are formed of these cavities between the coverplate and soleplate and a special full size aluminum sealing gasket is clamped between. The sealing surface around the steam generating cavity may be offset from the sealing surface around the distributing cavity and, when used, there is provided an aluminum-sealing member in the form of a smaller or partial gasket disposed between the cover and soleplate in the offset. The sealing gasket has at least one and preferably a pair of parallel continuous deforma-' ble U-shaped adjacent sealing ridges that extend along the entire sealing surface and are contiguous therewith. A silicone coating may be applied along the sealing surface and, if applied, it is disposed between either plate and the sealing gasket. The gasket is thin and deformable and in the range of 0.004 to 0.015 inch thick with its ridges having a height to width ratio in the range of from 2 to I up to,l to 3. The smaller gasket provides substantially coplanar sealing surfaces in the cover by being disposed in the offset and means is provided to clamp either sealing gasket between the coverplate and soleplate to flatten or crush the ridges and form a pressure seal between the cavities. Thus, the main object of the invention is applicable to a steam or steam-powered spray iron and is directed to providing an improved aluminum-sealing structure between the coverplate and soleplate and between the cavities to simplify, reduce the number of parts, and provide a long-life and effective seal.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a side elevation, partially in section, showing the location of the invention in a flat iron;

FIG. 2 is a plan view of a full-size ridged aluminum gasket as used in the invention;

FIG. 3 is a similar view of a preferred reduced size ridged aluminum gasket of lower cost; and

FIG. 4 is a cross section on line 44 of FIG. 2 showing the deformable ridge structure.

Referring to FIG. I, an iron embodying this invention generally has a soleplate 10, connected outer cover 12, and operating handle 14. In accordance with conventional practice, soleplate 10 may be cast from aluminum with an electrical heating element cast into position. The heating element preferably is of the sheathed type in which an electrical resistance element 16 extends through an outer tubular protective sheath with the heating element separated from the outer sheath by an electrical insulating compound resistant to heat such as a mass of granulated and compressed magnesium oxide. The temperature of the soleplate is set by temperature control knob 18 connected to operate a thermostat as well known in the art. In the usual manner, the heating element extends in a loop from the rear of the iron along one side to the forward or pointed end and then rearwardly along the other side. Thus, a substantially uniform heat distribution is provided, especially when an aluminum soleplate is employed.

Since spray irons are generally found in combination with steam irons, it is in this context that the invention is described and, more particularly, in connection with a steam-powered spray iron where a higher pressure steam may be employed although the invention is equally applicable to any steam iron. For steam generation, soleplate is provided with a steam generator in the form of cavity 20. A water tank 21 supplies water to orifice 22 in valve body 24 under control of valve stem 26 that is actuated by stepped button 28 by suitable known linkage mechanism whereby water drips onto the hot soleplate and is converted into steam. The steam so generated is confined and directed over the heated upper surface of the soleplate by a coverplate such as aluminum coverplate 30 which, with the soleplate 10, covers the steam-generating cavity to form a chamber and confine the steam. The steam thus generated flows into a collecting dome 32 that is tightly sealed to coverplate 30 in any suitable fashion and also supports various components of the iron including valve body 24. Exit of the steam from the generating cavity 20 is controlled by a pressure-regulating valve 34 to direct steam downwardly into a steam-distributing cavity 36 and thence out steam outlets 38. Pressure balance tube 40 transmits pressure from the steam-generating cavity to the upper portion of the water tank 21 to equalize pressure in the water tank and steam-generating cavity. All connections to the steam dome are liquidtight, accomplished by brazing, metal spinning, or other well-known techniques. A uniform operating steam pressure is maintained by the steam pressure regulator 34 which also determines the pressure under which the liquid spray nozzle operates. A regulator of this type is shown in US. Pat. No. 3,041,757 of common assignment. The steam produced in generator 20, as controlled by regulator 34, is directed upwardly for downward flow through the pressure regulator and thence through steam outlets 38 to the ironing surface. Pressure regulator 34 maintains a small pressure suitable for spray operation.

The iron is operable as a dry iron, as a steam iron, or as a liquid sprayer through a sprayer head 42. By closing orifice 22 to shut off water flow to steam cavity 20 the iron is a dry iron. Operation in the position shown in FIG. 1 provides steam for both the sprayer 42 and steam outlets 38 at the ironing surface. The structure thus described is conventional and generally shown in the US. Pat. No. 3,041,757 referenced.

In such an iron, it is necessary to provide a seal between coverplate 30 and soleplate 10 in order to separate the steam generated in cavity 22 from the same or lower pressure steam in distribution cavity 36. Obtaining a permanent seal between the soleplate and coverplate has presented a problem and many materials have been tried with the most successful being a silicone. However, deteriorating silicone deposits on the internal parts of the iron tend to cause those parts to become nonwettable by water, a phenomenon known as drifilm. Multiple sealing structures of layered construction have been suggested with the usual difficulty of complexity and resulting high costs. In a fiat iron the clamping pressure holding coverplate 30 to the soleplate is obtained by clamping screws 44 and the clamping pressure is relatively small as compared to other applications as in a head gasket. Merely increasing the clamping pressure by using more screws is not practical because that reduces the available space for channeling the steam through the distribution cavity and it also adds cost. It is possible to strengthen the coverplate by adding ribs but this would increase the pressure only by a small amount which would still be very low. The actual torque applied in a practical embodiment is about 27 inch pounds on each screw, so it can be seen that the clamping pressure is very small. Merely tightening the screws to apply additional pressure distorts the aluminum coverplate, which in turn destroys the seal that is required. It is impractical to increase the coverplate strength by using another material because stronger materials such as stainless steel are very costly to form in the configurations necessary to fulfill all of the functions required of the coverplate.

The gasket must be sufficiently rigid as to handle without permanent deformation when it is picked up for assembly, yet the rib(s) must crush when the light clamping force is applied.

A flat gasket of soft lead has been tried, but under test, it leaked too much. Similarly, various stainless steel alloy gaskets were too hard to seal well and are incompatible with the aluminum soleplate alloy as they apparently set up a microvoltage causing corrosion. As noted above, silicone alone eventually powders to permit leaks as well as creating the drifilm problems due to the substance given off as it deteriorates and dries out.

To meet the conditions, this invention provides a specifically structured aluminum gasket between the coverplate and soleplate which has solved theproblems and proved satisfactory. Referring next to FIGS. 2-4, a satisfactory and inexpensive, tested, and long-life sealing member is shown. As seen in FIG. 2, this may comprise a full-size thin aluminum gasket 46 that may cover a large portion of the entire area between the coverplate 30 and soleplate 10 and separate the generating cavity 20 from the distributing cavity 36 by at least one and preferably a pair of parallel spaced continuous and deformable U-shaped adjacent sealing ridges 48, the ridge structure running along the entire periphery or contiguous to the entire sealing surfaces 50 between these two cavities. Thus, an unbroken shaped ridge runs along the entire sealing surface. In the application ofa full-size gasket shown in FIG. 2, a similar single ridge 52 is sufficient between the distributing cavity 36 and the outside since back pressure from the closure of outlets 38 when pressed on a fabric is only slightly above ambient and therefore lower than the pressure in distributing cavity 20. The various openings shown in the gasket of FIG. 2 are merely openings required for the passage of steam from the generating cavity to the distribution cavity depending upon the casting formation of the particular coverplate and soleplate cavity.

In order to reduce the cost and still provide an effective seal, the modification of FIG. 3, showing a partial thin aluminum gasket may be used. This gasket has a slightly different shape for the central portion of the gasket of FIG. 2, being the part that surrounds generating cavity 20. In other words, it is the double-ridged portion with a suitable forward tab portion 54 surrounding the pressure regulator 34. In this preferred and less expensive modification, an offset 56 is provided in the sealing surface around the distributing cavity as shown in FIG. 1. While this offset may be in either the soleplate or coverplate, it is convenient to put it in the coverplate as shown. The smaller gasket of FIG. 3 has a flattened end 58 so that the gasket may be disposed in the offset to mesh with the cover and provide a coplanar sealing surface 60 with the soleplate. Of course, with a full gasket covering the full extent of the mating or sealing surfaces as shown in FIG. 2, no offset is required but the smaller gasket of FIG. 3 is a cost improvement and performs satisfactorily so is preferred.

The particular aluminum gasket is of a suitable alloy for low corrosion and one in which the ridges 48 do not work harden. Generally, the thickness of the gasket found to be satisfactory is 0.004 to 0.0l5 inch and the U-shaped ridges 48, as seen in FIG. 4, have been designed to have a height to width ratio in range of 2 to I up to l to 3. It has been found that ridges too narrow are too rigid to collapse easily and those that are too wide simply do not seal any more than a flat gasket. In the particular flexible metallic aluminum gasket, the ridges tend to crush under the light pressure of clamping screws 44 so that the apex of the U collapses or flattens and spreads out to a W cross section. Thus, the ridges must be collapsible or deformable to seal properly. Beyond the ratios given sufficient collapsing is not possible under the small clamping force used in irons. Further, a gasket of too rigid material, e.g. stainless steel, not only presents corrosion problems but prevents tightening down the coverplate without deforming the steam chamber cover and any such deformation leads to leaks and is completely unacceptable.

Thus, the aluminum-sealing gasket is of a material that is compatible with the coverplate and soleplate, so that it does not corrode itself or cause corrosion of the other parts. The width, height and strength of the material are sufficient to effect a seal, but not so rigid as to deform the steam chamber cover when the screws 44 pull the parts together. An excellent seal has been obtained with this aluminum gasket structure by applying the usual silicone coating along the sealing surface and disposing the silicone between either the soleplate and sealing gasket or the coverplate and the sealing gasket as shown at 62 in FIG. 4. The latter is easier since the silicone may be more easily applied to the coverplate by rolling it on because of the dishlike formation of the coverplate which accepts the silicone only at the high points. The actual preparation consists of applying the silicone with a paste solvent to the coverplate, then blowing warm air over it to dry and remove the solvent and leave the silicone tacky. The gasket is then applied to the tacky silicone and the entire assembly is heated after the parts havebeen screwed together. It has been found that repeated tests of the seal of this silicone-ridged aluminum gasket structure over a range from room temperature to 500 F. shows that efficiency of the seal actually improves with age. This improvement is not temporary but is retained for many cycles. It is thought that the subsequent powdering of the silicone may fill small leaks that may develop in the ridges of the aluminum gasket, but the leaks are not large enough to cause the silicone to be blown out, i.e., the aged powdered silicone merely clogs any leaks that tend to develop. Also, the deteriorated silicone does not wet with water so the surface tension of the water prevents seepage when the soleplate is cool.

It will be apparent that the use of the aluminum gasket resists steam, does not corrode, and is compatible with the adjacent parts. Further, the aluminum does not degrade to produce compounds to cause drifilming. Depending on which aluminum gasket with the continuous ridging is used, such as FIGS. 2 or 3, a silicone sealant may be applied only to the outer sealing periphery or all the ridges or merely between the coverplate and soleplate to seal the area between the cavities.

While there have been described preferred forms of the invention, obvious equivalent variations are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced, otherwise than as specifically described, and the claims are intended to cover such equivalent variations.

lclaim:

1. In a steam iron, a soleplate having a steam generating cavity and a steam-distributing cavity connected to a series of steam discharge apertures, and manual means to initiate water flow and subsequent steam flow from the generating cavity, the improvement in sealing structure comprising,

a coverplate over said cavities to form chambers thereof with the soleplate,

an aluminum sealing member between said coverplate and soleplate and having at least one continuous deformable U-shaped sealing ridge contiguous with the periphery of the sealing surface, and

means to clamp said member between said plates to flatten said ridge and form a pressure seal therebetween and between said cavities.

2. Apparatus as described in claim 1 having a silicone coating along the sealing surfaces between either plate and sealing member.

3. Apparatus as described in claim 1 having at least two parallel spaced continuous deformable U-shaped adjacent sealing ridges contiguous with the periphery of the sealing surface between the cavities.

4. Apparatus as described in claim 3 having a silicone coating along the sealing surfaces between the coverplate and sealing member.

5. In a steam-powered spray iron, at soleplate having a steam-generating cavity and a steam-distributing cavity connected to a series of steam discharge apertures, pressure regulating means between the cavities to control steam flow to the apertures and manual means to actuate said sprayer under steam pressure from the generating cavity, the improvement in sealing structure between said cavities comprising,

a coverplate over said cavities to form chambers thereof with the soleplate, I the sealing surface around said steam cavity being offset from the sealing surface around the distributing cavity, an aluminum-sealing member between said cover and soleplate disposed in the offset sealing surface, said member having a pair of parallel spaced continuous deformable U-shapcd adjacent sealing ridges contiguous with said offset sealing surface, and

means to clamp said member between said plates to flatten said ridges and form a pressure seal between said cavities.

6. Apparatus as described in claim 5 having a silicone coating along at least the sealing surface around the generating cavity and being disposed between either plate and sealing member.

7. Apparatus as described in claim 6 wherein said sealing member is 0.004 to 0.015 inch thick and said offset is disposed in said cover and provides substantial coplanar sealing surfaces in said cover around said cavities when said member is in place.

8. Apparatus as described in claim 7 wherein said ridges have a height to width ratio in the range of from 2 to 1 up to l to 3. 

1. In a steam iron, a soleplate having a steam generating cavity and a steam-distributing cavity connected to a series of steam discharge apertures, and manual means to initiate water flow and subsequent steam flow from the generating cavity, the improvement in sealing structure comprising, a coverplate over said cavities to form chambers thereof with the soleplate, an aluminum sealing member between said coverplate and soleplate and having at least one continuous deformable U-shaped sealing ridge contiguous with the periphery of the sealing surface, and means to clamp said member between said plates to flatten said ridge and form a pressure seal therebetween and between said cavities.
 2. Apparatus as described in claim 1 having a silicone coating along the sealing surfaces between either plate and sealing member.
 3. Apparatus as described in claim 1 having at least two parallel spaced continuous deformable U-shaped adjacent sealing ridges contiguous with the periphery of the sealing surface between the cavities.
 4. Apparatus as described in claim 3 having a silicone coating along the sealing surfaces between the coverplate and sealing member.
 5. In a steam-powered spray iron, a soleplate having a steam-generating cavity and a steam-distributing cavity connected to a series of steam discharge apertures, pressure regulating means between the cavities to control steam flow to the apertures and manual means to actuate said sprayer under steam pressure from the generating cavity, the improvement in sealing structure between said cavities comprising, a coverplate over said cavities to form chambers thereof with the soleplate, the sealing surface around said steam cavity being offset from the sealing surface around the distributing cavity, an aluminum-sealing member between said cover and soleplate disposed in the offset sealing surface, said member having a pair of parallel spaced continuous deformable U-shaped adjacent sealing ridges contiguous with said offset sealing surface, and means to clamp said member between said plates to flatten said ridges and form a pressure seal between said cavities.
 6. Apparatus as described in claim 5 having a silicone coating along at least the sealing surface around the generating cavity and being disposed between either plate and sealing member.
 7. Apparatus as described in claim 6 wherein said sealing member is 0.004 to 0.015 inch thick and said offset is disposed in said cover and provides substantial coplanar sealing surfaces in said cover around said cavities when said member is in place.
 8. Apparatus as described in claim 7 wherein said ridges have a height to width ratio in the range of from 2 to 1 up to 1 to
 3. 